1. Field of the Invention
The present invention pertains to image processing technology suitable for game devices and various simulators (virtual reality devices) that conduct three-dimensional (3D) image display.
2. Description of the Related Art
A game device for shooting a target character (e.g., an enemy such as a person) appearing on the screen with a gun-shaped controller having a shape imitating a gun is conventionally known. With this kind of shooting game or the like, in addition to a game which is played by operating a player character displayed on the screen, there is a game which conducts a so-called first person point of view by displaying the status in the virtual space (game space) viewed from the operator's viewpoint on the screen. As a result of such first person point of view being displayed as an image, the operator will be able to enjoy a sensation of aiming at a target object (an enemy character, for example) in the virtual space from the muzzle of the gun-shaped controller operated by such operator in the real space. Image display technology of such first person point of view is described, for instance, in Japanese Patent Laid-Open Publication No. H8-69274.
In a shooting game, it is preferable to adopt the display method of displaying the trajectory of the bullet fired from the player character's gun since the expressiveness of the game image will be enhanced. Nevertheless, when adopting the image expression of the first person point of view described above, it was difficult to effectively express the trajectory of the bullet. Specifically, upon adopting the image expression of the first person point of view, generally speaking, a position roughly matching the operator's viewpoint or a position of the muzzle near such position is set as the virtual viewpoint, and a two-dimensional image (game image) is generated by performing projective transformation to the inside of the game image and projecting this on a prescribed projection plane in correspondence with this virtual viewpoint. Nevertheless, when the position of this virtual viewpoint is set to the operator's viewpoint or a position in the vicinity thereof, since the trajectory of the bullet will also head toward the aimed position from the virtual viewpoint or a position in the vicinity thereof, the trajectory in the two-dimensional image obtained pursuant to the projective transformation will be displayed in an approximate point-like pattern, and the trajectory of the bullet cannot be sufficiently expressed.